Tin-containing ceramic composition

Abstract

Superconductors having a composition Bi 2-a-b-c Sn a Pb b Sb c Sr 2 Ca n-1 Cu n O 2n+4 can be made by firing the appropriate mixtures of designated oxides or carbonates. In the composition a=about 0.001-0.4, b about 0-0.4, c about 0-0.4, and n 2 or 3. The addition of Sn improves the superconductive properties of comparable compositions that lack Sn. For example, Bi 1 .6 Sn 0 .4 Sr 2 Ca 2 Cu 3 O x (x=ca 10), calcined at 830° C. for 15 hours shows superconductivity by magnetic susceptibility tests at about 77° K. whereas Bi 2 Sr 2 Ca 2 Cu 3 O 10 prepared under the same conditions but lacking Sn, shows nothing at this temperature.

I claim: 
     
       1. A superconductor composition Bi 2-a-b-c  Sn a  Pb b  Sb c  Sr 2  Ca 2  Cu 3  O x  where a=about 0.001-0.4, b=about 0-0.4, c=about 0-0.4, a+b+c=about 0.4-0.5 and x=about 10. 
     
     
       2. Composition according to claim 1 wherein a=about 0.1-0.4, b=about 0.1-0.4, and c=about 0.1-0.2. 
     
     
       3. Composition according to claim 2, Bi 1 .6 Sn 0 .4 Sr 2  Ca 2  Cu 3  O x . 
     
     
       4. Composition according to claim 2, Bi 1 .5 Pb 0 .4 Sn 0 .1 Sr 2  Ca 2  Cu 3  O x . 
     
     
       5. Composition according to claim 2, Bi 1 .5 Pb 0 .3 Sn 0 .1 Sb 0 .1 Sr 2  Ca 2  Cu 3  O x . 
     
     
       6. Composition according to claim 2, Bi 1 .6 Sb 0 .2 Sn 0 .2 Sr 2  Ca 2  Cu 3  O x .